Anti-chatter guides for spade drill

ABSTRACT

Anti-chatter guides for a spade drill which are perpendicular to the side faces of the spade blade and which have an end to end dimension (diameter) wholly forwardly of the rear portion of the blade corresponding to the width of the blade so as to engage the wall of the hole drilled by the blade thus to prevent chatter of the spade drill during drilling and after the cutting edges break through the workpiece. In one form of the invention, the guides constitute a portion of the clamping means by which the spade blade is mounted in the slotted end of a holder, and in another form of the invention, the guides are on the blade itself forwardly of the holder.

United States Patent Benjamin et al.

' 3,658,434 451 Apr. 25, 1972 ANTI-CHATTER GUIDES FOR SPADE DRILLInventors: Milton L. Bertiamin; David D. Walker,

both of Chagrin Falls, Ohio Assignee: Erickson Tool Company, Solon, OhioFiled: Apr. 3, 1970 Appl. No.: 25,382

U.S. Cl ..408/200, 408/83, 408/114, 408/239 Int. Cl ..B23b 51/00 Fieldof Search ..408/83, l 13, 114, 200, 211, 408/239 References Cited UNITEDSTATES PATENTS 12/1895 King .,..408/200 Primary Examiner-Francis S,Husar Attorney-Oberlin, Maky, Donnelly & Renner [5 7] ABSTRACTAnti-chatter guides for a spade drill which are perpendicular to theside faces of the spade blade and which have an end to end dimension(diameter) wholly forwardly of the rear portion of the bladecorresponding to the width of the blade so as to engage the wall of thehole drilled by the blade thus to prevent chatter of the spade drillduring drilling and after the cutting edges break through the workpiece.In one form of the invention, the guides constitute a portion of theclamping means by which the spade blade is mounted in the slotted end ofa holder, and in another form of the invention, the guides are on theblade itself forwardly of the holder.

6 Claims, 4 Drawing Figures PATENTEmvRzslevz 3658, 134

INVENTORS 29 MILTON L. BENJAMIN DAV/D 0. WALKER ATTOR NEYS ANTI-CHATTERGUIDES FOR SPADE DRILL BACKGROUND OF THE INVENTION As shown in theMilton L. Benjamin et al. U. S. Pat. Nos. 3,049,033, 3,076,357, and3,364,800, spade drills generally comprise a flat blade having cuttingedges at one end and having a hole therethrough adjacent the rear endthrough which a screw extends for clamping the blade in the slotted endof a holder, the holder usually having a shank for mounting the holderin a machine tool spindle, in a lathe turret or the like. From thelast-mentioned patent it is known to provide carbide or like guidebuttons mounted in the holder rearwardly adjacent the rear end of theblade. However, if the axial length of the blade exceeds the thicknessof the workpiece, the cutting edges of the blade may break through theworkpiece before the guide buttons of US. Pat. No. 3,364,800 enter thedrilled hole, whereby they are not effective to reduce chatter untilafter the axially rear portion of the blade has entered the hole.

SUMMARY OF THE INVENTION Contrary to the foregoing, the anti-chatterguides herein are secured in a hole in the blade which is forward of therear end thereof, thus to become effective to reduce chatter during thedrilling operation and when the cutting edges break through theworkpiece.

Furthermore, the anti-chatter guides herein are secured against relativerotation with respect to the hole in the blade so that the outer ends ofthe guides may have the same shape as the hole being drilled withoutpossibility of skewing of the end surfaces of the guides.

The anti-chatter guides herein also constitute a portion of the clampingmeans by which the blade is secured ,in the holder.

Other objects and advantages of the present invention will appearhereinafter.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a side elevation view of theend portion of a spade drill blade holder with a blade clamped therein;

FIG. 2 is a cross-section view taken substantially along the line 22,FIG. I;

FIG. 3 is a fragmentary side elevation view of the front end portion ofa modified form of blade embodying the present invention; and

FIG. 4 is a cross-section view taken substantially along line 4-4, FIG.3.

DETAILED DESCRIPTION OF THE INVENTION As shown in FIGS. 1 and 2, the endof the holder 1 has a diametrical slot 2 which is of width correspondingto the thickness of the blade 3 adapted to be mounted therein in seatedengagement against the bottom 4 of the slot 2 with axial portions 5 ofthe blade 3 overlapping flat portions 6 of the holder 1 thus to alignthe blade 3 and holder 1 axes. The holder 1 is formed with flutes 7which extend longitudinally for travel of chips away from the cuttingedges 8 of the blade 3. As shown in the aforesaid Milton L. Benjamin etal. patents, the holder 1 will be provided with a suitable shank at itsrear end (not shown herein) for connection with a machine tool spindleor with a lathe turret or the like.

The slotted end of the holder 1 has a hole 9 therethrough perpendicularto the slot 2 which registers with the hole 10 of the blade 3, the hole9 being counterbored at its opposite ends to receive anti-chatter guides11 and 12 therein, the guides 11 and 12 being keyed against rotation asby means of cylindrical pins I4 and 15 which are press-fitted into theholder 1 and which extend into semi-circular axial grooves 16 and 17 ofthe respective guides 11 and 12. One guide 11 is counter bored toreceive the head 18 of a clamping screw 19 and the other slotted end ofthe holder I is caused to tightly frictionally clamp the blade 3therein.

In the case of the drilling of a round hole in a workpiece, the outerends of the guides 11 and 12 are cylindrical and are of the samediameter asthe width of the blade which preferably has cylinder groundopposite sides 21.

The blade 3 herein shown is of conventional form having cutting edges 8provided with top rake grooves 23 and having relief 24 on the cuttingedges 8. The sides of the blade 3 are as aforesaid preferably cylinderground as at 21 with relief 25.

Referring now to FIGS. 3 and 4, the blade 26 has antichatter guides 27and 28 in lieu of, or in addition to, the guides 11 and 12 shown inFIGS. 1 and 2. The guides 27 and 28 are piloted in the hole 29 in thefront end portion of the blade 26 just behind the cutting edges 30 andare held against rotation with respect to the blade 26 and with respectto each other as by means of the key 31 engaged in keyways formed in therespective guides 27 and 28 and in the hole 29. Clamping of the guides27 and 28 to the blade 26 is effected by a screw 32 having its headengaged in a counterbore in one guide 27 and having threaded engagementwith the other guide 28. As in the case of the blade 3 and guides 11 andI2, the sides of the blade 26 and the outer ends of the guides 27 and 28are cylinder ground whereby the guides 27 and 28 prevent chatter of theblade 26 as when the cutting edges 30 break through a workpiece.

We, therefore, particularly point out and distinctly claim as ourinvention:

1. A spade drill comprising a holder having an axial slot diametricallyacross one end; a blade in said slot having cutting edges axially beyondthe end of said holder, and diametrically opposite axial side faces toguide said drill into the hole formed by said cutting edges as saiddrill and a workpiece are relatively rotated and fed axially;diametrically opposite anti-chatter guide means on said holder disposedperpendicular to said slot and blade and having a diametrical endto-enddimension substantially equal to the distance between said side faces tofurther guide said drill and to substantially eliminate chatter of saiddrill; and screw means operative to secure said anti-chatter guide meansto said holder and to clamp said blade in said slot; said screw meanscomprising a screw extending through registering holes in said holderand said blade, said screw having a head engaging one of said guidemeans and having threaded engagement with the other of said guide means.

2. The spade drill of claim 1 wherein the hole in said holder iscounterbored at its ends to receive therein the respective guide means.

3. The spade drill of claim 2 wherein said one guide means iscounterbored to receive the head of said screw therein.

4. The spade drill of claim 2 wherein key means in said counterbores areengaged with the respective guide means to retain them from rotationrelative to each other and to said holder about the axis of the hole insaid holder.

5. A spade drill comprising a holder having an axial slot diametricallyacross one end; a blade in said slot having cutting edges axially beyondthe end of said holder, and diametrically opposite axial side faces toguide said drill into the hole formed by said cutting edges as saiddrill and a workpiece are relatively rotated and fed axially;diametrically opposite anti-chatter guide means disposed perpendicularto said blade and having a diametrical end to end dimensionsubstantially equal to the distance between said side faces to furtherguide said drill and to substantially eliminate chatter of said drill;screw means operative to clamp said blade in said slot; the ends of saidguide means being disposed entirely within the axial extent of said sidefaces of said blade; key means retaining said guide means againstrotation with respect to each other and with respect to said blade; andadditional screw means operative to retain said guide means on saidblade forwardly of the slotted end of said holder.

6. The spade drill of claim 5 wherein said guide means are piloted in ahole in said blade forwardly of the slotted end of said holder; andwherein said additional screw means bears on one of said guide means andextends through the hole in said blade and has threaded engagement withthe other one of said guide means thus to clamp said guide means to saidblade.

1. A spade drill comprising a holder having an axial slot diametricallyacross one end; a blade in said slot having cutting edges axially beyondthe end of said holder, and diametrically opposite axial side faces toguide said drill into the hole formed by said cutting edges as saiddrill and a workpiece are relatively rotated and fed axially;diametrically opposite antichatter guide means on said holder disposedperpendicular to said slot and blade and having a diametrical end-to-enddimension substantially equal to the distance between said side faces tofurther guide said drill and to substantially eliminate chatter of saiddrill; and screw means operative to secure said antichatter guide meansto said holder and to clamp said blade in said slot; said screw meanscomprising a screw extending through registering holes in said holderand said blade, said screw having a head engaging one of said guidemeans and having threaded engagement with the other of said guide means.2. The spade drill of claim 1 wherein the hole in said holder iscounterbored at its ends to receive therein the respective guide means.3. The spade drill of claim 2 wherein said one guide means iscounterbored to receive the head of said screw therein.
 4. The spadedrill of claim 2 wherein key means in said counterbores are engaged withthe respective guide means to retain them from rotation relative to eachother and to said holder about the axis of the hole in said holder.
 5. Aspade drill comprising a holder having an axial slot diametricallyacross one end; a blade in said slot having cuttiNg edges axially beyondthe end of said holder, and diametrically opposite axial side faces toguide said drill into the hole formed by said cutting edges as saiddrill and a workpiece are relatively rotated and fed axially;diametrically opposite anti-chatter guide means disposed perpendicularto said blade and having a diametrical end to end dimensionsubstantially equal to the distance between said side faces to furtherguide said drill and to substantially eliminate chatter of said drill;screw means operative to clamp said blade in said slot; the ends of saidguide means being disposed entirely within the axial extent of said sidefaces of said blade; key means retaining said guide means againstrotation with respect to each other and with respect to said blade; andadditional screw means operative to retain said guide means on saidblade forwardly of the slotted end of said holder.
 6. The spade drill ofclaim 5 wherein said guide means are piloted in a hole in said bladeforwardly of the slotted end of said holder; and wherein said additionalscrew means bears on one of said guide means and extends through thehole in said blade and has threaded engagement with the other one ofsaid guide means thus to clamp said guide means to said blade.